Jump to main content or area navigation.

Contact Us

Human Exposure and Atmospheric Sciences

Ecosystems

EPA exposure scientists are developing methods and tools to determine the risks that contaminants from various sources pose to ecosystems. Critical areas of research focus on utilizing laboratory and computer-based methods to determine how the transformation and fate of air toxins impact our environment. Studies have also been conducted on silver nanoparticles, with the goal of better understanding how nano-scale silver, used in a variety of consumer products, moves through the environment and transforms under different product use scenarios.

Computational atmospheric chemistry helps EPA scientists forecast future atmospheric conditions
EPA scientists have developed an innovative computational chemistry-based method called COMPCHEM that is used for predicting lifetimes and fates of atmospheric compounds. COMPCHEM consists of a set of well-established, state of the science, quantum chemistry and gas phase kinetic codes, all of which have been used in numerous studies reported in peer-reviewed literature. It is anticipated that COMPCHEM will be a cost effective tool for supplementing atmospheric chemistry data generated through laboratory studies.

Sophisticated test chambers used to simulate atmospheric conditions
EPA scientists are using experimental laboratory studies to gather and assess data on atmospheric gas phase and particulate phase chemistry in order to determine the effects that various source emissions have on humans and ecosystems. Researchers are also working on the construction and development of a new, mobile photochemical reaction chamber to be used to study the toxicity of combustion emission sources. Research results are anticipated improve understanding of how atmospheric reactions and transformations influence the toxicity of air pollutant mixtures.

Nanosilver and consumer products
EPA scientists are conducting research to determine whether consumer products containing nano-silver are releasing nanoparticles in unintended ways. EPA scientists are also conducting studies to examine chemical and physical changes that might occur in silver nanoparticles that are ingested with food or water by exposing the nanoparticles to synthetic human stomach fluid. To be protective of human health, EPA scientists and regulators must understand how nano-scale silver — used in a variety of consumer products — moves through the environment and transforms under different product use scenarios.

Positive Matrix Factorization (PMF) Model
EPA’s Positive Matrix Factorization (PMF) Model is one of several receptor models developed by EPA scientists that provide scientific support for current ambient air quality standards and implementation of those standards by identifying and quantifying the relative contributions that various air pollution sources contribute to ambient air quality in a community or region. Users of EPA’s PMF model provide files of sample species concentrations and uncertainties which the model uses to calculate the number of sources types, profiles, relative contributions, and a time-series of contributions.

Unmix 6.0 Model
EPA’s Unmix 6.0 Model is one of several receptor models developed by EPA scientists that provide scientific support for current ambient air quality standards and implementation of those standards by identifying and quantifying the relative contributions that various air pollution sources contribute to ambient air quality in a community or region. Users of EPA’s PMF model provide files of sample species concentrations and uncertainties which the model uses to calculate the number of sources types, profiles, relative contributions, and a time-series of contributions.

Jump to main content.